Member for oil application device, method of manufacturing the member, and oil application device

ABSTRACT

A tubular member for an oil application device is formed separately and is fitted in such a manner as to cover a peripheral face of a porous cylindrical oil retaining member. The tubular member for the oil application device has a multi-layer structure including an inner layer and an outermost layer. The inner layer is a fibrous layer, and the outermost layer is a porous film. The porous cylindrical oil retaining member can be easily covered with, fitted with, and removed of the member for the oil application device, which is made from a fibrous layer such as a felt or from a porous film such as a PTFE film.

TECHNICAL FIELD

[0001] The invention relates to a member for an oil application devicewhich is a component of a fixing device of a capacitance type copyingmachine, an electrophotographic printer or the like. The invention alsorelates to a method of manufacturing such a member and to an oilapplication device.

BACKGROUND ART

[0002] In a fixing device of a capacitance type copying machine, anelectrophotographic printer or the like, during fixation of toner thathas been transferred to a recording paper, the toner may adhere to athermal fixing roller. In order to prevent the toner from soilinganother recording paper, a very small amount of releasing oil such assilicon oil is applied to the thermal fixing roll using an oilapplication device. Thus, toner is prevented from adhering to thethermal fixing roll, and recording papers are prevented from being stuckto one another and rolled up.

[0003] Various oil application devices having such a function havealready been proposed. For example, Japanese Patent ApplicationLaid-Open No. 2000-079365 discloses an oil application device that isdesigned such that a felt is wound around and bonded to a peripheralface of a cylindrical porous ceramic compact and that a PTFE film isbonded and fixed to a peripheral face of the felt.

[0004] Various methods are adopted to attach the felt layer to theperipheral face of the porous ceramic compact in the above-mentioned oilapplication device. According to one of such methods, a sheet-like feltfiber is wound around a peripheral face of a porous ceramic compact byone turn, an adhesive is applied to edges of end portions of the feltfiber, and opposed end faces thereof are bonded together and fixed.According to another one of such methods, an adhesive is applied toedges of a felt that has been cut into the shape of a ribbon strip, andthe felt is spirally wound around and fixed to a porous ceramic compactwhile the edges abut on each other without overlapping with each other.

[0005] On the other hand, in order to fix a PTFE film to a peripheralface of a felt, it is customary to apply an adhesive to the back of asheet-like PTFE film and wind the sheet-like PTFE film around aperipheral face of a felt layer so as to fix the sheet-like PTFE film tothe felt layer. A method of bonding in this case requires refinements.For instance, an adhesive is applied spirally or in a dotted manner soas to define a section to be bonded and guarantee oil for application ofa passage.

[0006] However, the oil application device constructed as describedabove requires separately bonding the felt and the PTFE film and is thustroublesome from the standpoint of processes of fabricating theapplication device. Further, seam portions of the spirally wound felt ismore obstructive to the transfer of oil than the other portions thereof,thus causing a problem of a decrease in amount of application of oil.Such seam portions of the felt exist over the entire peripheral face ofthe felt layer. Thus, if printing is carried out using this oilapplication device, streaky irregularities in gloss appear on the entiresurface of a printed matter.

[0007] On one hand, if the oil application device is used for a certainperiod, it runs out of oil held therein and requires being replenishedwith oil. The felt and the PTFE film are damaged after use for a certainperiod and have no choice but to be destroyed. In particular, the PTFEfilm is altered by being heated up to 150° C. or more at a fixingportion. In addition, the PTFE film suffers a severe deterioration suchas deformation or closure of open pore portions resulting from stains oftoner components, adhesion of toner components, and heat. It is thusimpossible to recycle the PTFE film. Further, the felt layer is alsodeprived of its flexibility by heat and can no longer guarantee uniformapplication of a predetermined amount of oil. Therefore, it is difficultto recycle the felt layer as in the case of the PTFE film.

[0008] On the other hand, the porous ceramic compact can be recycled ifit is impregnated with releasing oil again. However, the recycling ofthe porous ceramic compact requires peeling off the felt layer and thePTFE film. Even in an attempt to attach a brand-new felt and a brand-newPTFE film, they must be separately bonded with an adhesive as describedabove. This causes a problem of troublesomeness from the standpoint ofprocesses of reconstructing the oil application device.

[0009] It is thus an object of the present invention to provide a memberfor an oil application device which makes it easy for a porouscylindrical oil retaining member to be covered with, to be fitted with,or to be removed of a member made from a fibrous layer such as a felt orfrom a porous film such as a PTFE film. It is also an object of thepresent invention to provide a method of manufacturing such a member andan oil application device employing the member.

DISCLOSURE OF THE INVENTION

[0010] The inventors conducted studies wholeheartedly under suchcircumstances and have discovered the following facts. That is, asheet-like felt is formed into a tubular object, for example, using adummy cylindrical mold. A PTFE film is then fixed to a peripheral faceof the tubular object with an adhesive or the like, and the tubularobject is drawn out of the dummy cylindrical mold, so that a tubularmember having a double-layer structure is obtained. A porous cylindricaloil retaining member can be easily covered with, fitted with, andremoved of this tubular member. Further, the sheet-like felt is fittedto the dummy cylindrical mold according to a method comprising the stepsof folding the sheet-like felt in two, sewing up end portions thereof,cutting off margins of the end portions if need be, reversing thesheet-like felt, and covering the dummy cylindrical mold with it. Thismethod ensures that the sewn-up portions are hidden inside, thus makingit possible to stabilize application performance. Finally the inventorssucceeded in completing the present invention.

[0011] That is, the present invention (1) provides a tubular member foran oil application device which has been formed separately so as tocover a peripheral face of a porous cylindrical oil retaining member,wherein the tubular member for the oil application device has amulti-layer structure including an inner layer and an outermost layer,wherein the inner layer is a fibrous layer, and wherein the outermostlayer is a porous film. Adoption of such a construction ensures that theporous cylindrical oil retaining member can be covered with the memberfor the oil application device easily, thus making it possible tofabricate the oil application device easily and enhance the overallproductivity. Further, if the porous cylindrical oil retaining member isrecycled, the member for the oil application device can be easilyremoved from the porous cylindrical oil retaining member, and can befixed thereto without using an adhesive during assembly. Therefore, theporous cylindrical oil retaining member is prevented from being soiledwith an adhesive, and the regeneration cost can be reduced.

[0012] Further, the present invention (2) provides the member for theoil application device wherein the fibrous layer is a fiber felt andwherein the porous film is a PTFE film. Adoption of such a constructionensures that the fiber felt can sufficiently perform the function of anoil transfer layer and that the PTFE film can sufficiently perform thefunction of an oil application amount control layer, thus making itpossible to guarantee a fixing roll of uniform application of apredetermined amount of oil without causing irregularities.

[0013] Further, the present invention (3) provides the member for theoil application device wherein the fibrous layer and the porous film arebonded together by the mixture of an adhesive and silicon oil. Adoptionof such a construction ensures that the adhesive components in theirsolidified state are dispersed into silicon oil and exist partiallyinside the open pores in the porous film, thus making it possible toenhance strength and durability of the porous film. On the other hand,since the mixture of the adhesive and silicon oil is microscopically ina state where the adhesive is dispersed into silicon oil, the siliconoil area serves as a passage for releasing oil inside the open pores.Accordingly, the open pores in the porous film are filled with themixture, whereby releasing oil is guaranteed of a passage despiteclosure of the open pores. Consequently, it becomes possible to apply asuitable amount of releasing oil and control the amount of applicationof releasing oil.

[0014] Further, the present invention (4) provides a method ofmanufacturing a member for an oil application device, comprising thesteps of winding a sheet-like fibrous material, which is longer than acircumferential length of a dummy cylindrical mold that is substantiallyequal in diameter to a porous cylindrical oil retaining member to becovered, around the dummy cylindrical mold by one turn so as to form afibrous layer, sewing up bonded portions, pressing at least the bondedportions so as to form a peripheral face, and winding a sheet-likeporous film around the peripheral face of the fibrous layer by one turnso as to bond the sheet-like porous film to the fibrous layer. Adoptionof such a construction makes it possible to fabricate the member for theoil application device reliably by a simple method. Further, since thesheet-like fibrous layer is formed into a cylindrical shape, the numberof seams in the fibrous layer is reduced. As a result, it becomespossible to achieve uniform application of oil without causingirregularities.

[0015] Further, the present invention (5) provides a method ofmanufacturing a member for an oil application device, comprising thesteps of folding a sheet-like fibrous material in two and sewing up endportions thereof, reversing the sheet-like fibrous material that hasbeen sewn up and covering a dummy cylindrical mold, which issubstantially equal in diameter to a porous cylindrical oil retainingmember to be covered, with the sheet-like fibrous material, and windinga sheet-like porous film around a surface of the sheet-like fibrousmaterial covering the dummy cylindrical mold by one turn so as to bondthe sheet-like porous film to the sheet-like fibrous material. Adoptionof such a construction makes it possible to fabricate the cylindricalmember for the oil application device easily. Also, this constructionmakes it possible to suppress the influence of the sewn-up portion andto apply oil uniformly without causing irregularities despite thesimplicity of processes of fabrication.

[0016] Further, the present invention (6) provides an oil applicationdevice having a porous cylindrical oil retaining member that is coveredon a peripheral face thereof with a tubular member for the oilapplication device which has been formed separately, wherein the tubularmember for the oil application device has a multi-layer structureincluding an inner layer and an outermost layer, wherein the inner layeris a fibrous layer, and wherein the outermost layer is a porous film.Adoption of such a construction realizes a simple structure in which theporous cylindrical oil retaining member is covered with the tubularmember for the oil application device which has been formed separately,thus making it possible to reduce the number of failures and to achievestable application of oil. Further, if the porous cylindrical oilretaining member is recycled, the tubular member for the oil applicationdevice can be easily removed from the porous cylindrical oil retainingmember. This makes it possible to enhance the workability duringrecycling.

[0017] Further, the present invention (7) provides the oil applicationdevice wherein the tubular member for the oil application device isfolded at opposed end portions thereof onto lateral faces of the porouscylindrical oil retaining member and wherein folded portions of thetubular member for the oil application device are pressed and fixed by afixture member. Adoption of such a construction makes it possible to fixthe tubular member for the oil application device to the porouscylindrical oil retaining member without using an adhesive.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIGS. 1(A) to 1(E) illustrate a procedure of manufacturing amember for an oil application device of the present invention.

[0019]FIG. 2 is a radial sectional view of the member for the oilapplication device of the present invention.

[0020] FIGS. 3(A) to 3(C) illustrate another procedure of manufacturingthe member for the oil application device of the present invention.

[0021] FIGS. 4(A) and 4(B) show a state where a porous cylindrical oilretaining member is covered with the member for the oil applicationdevice.

[0022]FIG. 5 is an axial sectional view of the oil application device ofthe present invention.

[0023]FIG. 6 is an enlarged view of an end portion of FIG. 5.

[0024]FIG. 7 is a side view showing a state where a fixing deviceemploys the oil application device according to an embodiment of thepresent invention.

DETAILED DESCRIPTION

[0025] First of all, a first method of manufacturing a member for an oilapplication device of the present invention will be described withreference to FIGS. 1 and 2. First of all, a sheet-like fibrous materialis wound around a dummy cylindrical mold 15 by one turn so as to form afibrous layer 11 (FIG. 1(A)). The dummy cylindrical mold 15 issubstantially equal in diameter to a porous cylindrical oil retainingmember to be covered (a later-described member denoted by a referencenumeral 2 in FIG. 4). The sheet-like fibrous material is longer than thecircumference of the dummy cylindrical mold 15. The dummy cylindricalmold 15 is designed to form the sheet-like fibrous material into atubular shape. It is to be noted herein that the sheet-like fibrousmaterial has a width equal to the sum of the length of the porouscylindrical oil retaining member to be covered later and the length ofportions folded onto opposed ends thereof. Further, the dummycylindrical mold 15 preferably has a diameter which is 95% to 105% ofthe diameter of the porous cylindrical oil retaining member. Morepreferably, the dummy cylindrical mold 15 has a diameter equal to orapproximately 1 to 5% larger than the diameter of the porous cylindricaloil retaining member. If the sheet-like fibrous material is flexibleenough, the dummy cylindrical mold 15 may preferably have a diameterapproximately 1 to 5% smaller than the diameter of the porouscylindrical oil retaining member. A reference numeral 16 denotes ashaft.

[0026] When the oil application device is formed, the sheet-like fibrousmaterial serves as an oil transfer layer. A heat-resistant fiber feltcan be used as the sheet-like fibrous material. This heat-resistantfiber felt is obtained, for example, by forming fiber material groupsinto a plate-like web by roller forming and then processing the web byneedle punching. The heat-resistant fiber felt is made from a fibermaterial with a diameter of approximately 10 μm and has athree-dimensional flexible network structure with a weight ofapproximately 200 to 800 g/m², a thickness of 1 to 5 mm, and a densityof 170 to 260 kg/m³.

[0027] The sheet-like fibrous material is wound around the dummycylindrical mold 15 by one turn, and has bonding edges 18 formed atopposed end portions thereof. The bonding edges 18 at the opposed endportions abut on each other, and root portions thereof are bondedtogether. Although a method of bonding the root portions is notspecifically limited, they can be bonded easily and reliably by beingsewn up using a thread 17 (FIG. 1(B)). After the bonded portions havebeen sewn, two bonding edges located above the sewn portions are openedin opposed directions (FIG. 1(C)).

[0028] Then, at least the bonded portions are pressed inwards so as toshape a peripheral face (FIG. 1(D)). Preferably, the entire peripheralface of the fibrous layer 11 is pressed inwards. The shaping of theperipheral face is preferably carried out such that the bonded portionsare not protrusively strained and that a smooth periphery is formed.

[0029] After the bonded portions have been pressed, a sheet-like porousfilm is wound around the peripheral face of the fibrous layer 11 by oneturn and bonded thereto (FIG. 1(E)). When the sheet-like porous film iswound around the peripheral face of the fibrous layer 11 by one turn,the porous film 3 has edges thereof overlapping with each other by awidth of approximately 1 to 20 mm. When the oil application device isformed, the sheet-like porous film serves as an oil application amountcontrol layer. The sheet-like porous film is not specifically limited aslong as silicon oil permeates therethrough. For example, an elongatedpolytetrafluoroethylene (PTFE) porous film can be used as the sheet-likeporous film. For example, the PTFE film used herein demonstrates asurface roughness Ra of 0.7 to 0.8 μm, a thickness of 20 to 100 μm, agas permeability of 5 to 100 seconds/100 cc, an open pore diameter of0.05 to 2.0 μm, and an open pore rate of 70 to 90%. “Gas permeability”represents a Gurley number (unit: seconds/100 cc) measured by a B-typeGurley densometer. “Open pore rate” represents a value calculated from aspecific weight measurement according to the following equation: openpore rate (%)=(1-bulk specific gravity/absolute specific gravity)×100.

[0030] It is preferable that the peripheral face of the fibrous layer 11and the sheet-like porous film be bonded together by the mixture of anadhesive and silicon oil. It is important for this mixture that theadhesive and silicon oil be mixed with each other sufficiently and bedispersed into each other. It is preferable to use silicon varnish asthe adhesive. For example, it is possible to use the mixture having sucha mixture ratio that silicon varnish constitutes 70 weight % and thatsilicon oil constitutes 30 weight %. Although both entire bonging andpartial bonding are acceptable, the former is preferred because it canenhance a bonding strength of the porous film 3 and thus achieve higherreliability. In the case of entire bonding, the mixture is applied tothe back (bonding surface) of the porous film 3, for example, with asurface density of 10 to 250 g/m². The surface is laminated onto thefibrous layer 11 and dried for 1 to 4 hours so as to solidify adhesivecomponents. Because the adhesive components in their solidified stateare thus dispersed into silicon oil and exist partially inside the openpores, it is possible to further enhance strength and durability of theporous film 3. On the other hand, the mixture of the adhesive andsilicon oil is microscopically in a state where the adhesive isdispersed into silicon oil. Therefore, the silicon oil area constitutesa passage for releasing oil inside the open pores. Accordingly, the openpores in the porous film 3 are filled with the mixture, wherebyreleasing oil is guaranteed of a passage despite closure of the openpores. Consequently, it becomes possible to apply a suitable amount ofreleasing oil and control the amount of application of releasing oil.

[0031] Next, a tubular double-layer structure composed of the fibrouslayer 11 and the porous film 3 is removed from the dummy cylindricalmold 15. As a method of removal, it is appropriate that the dummycylindrical mold 15 be fixed and that the tubular double-layer structurebe drawn from the dummy cylindrical mold 15 on one side thereof.Thereby, a member 20 for the oil application device of the presentinvention can be obtained (FIG. 2). The member 20 for the oilapplication device of the present invention has a double-layer structurecomposed of inner and outer layers. The inner layer is the fibrous layer11, and the outer layer is the porous film 3.

[0032] A second method of manufacturing the member for the oilapplication device of the present invention will be described withreference to FIG. 3. First of all, a sheet-like fibrous material 11 a isfolded in two and is sewn up at end portions thereof so as to form abag-shaped object (FIG. 3(A)). It is to be noted herein that the innerdiameter of the bag-shaped object is substantially equal to the outerdiameter of the dummy cylindrical mold 15 with which the bag-shapedobject is to be covered later. In FIG. 3(A), reference numerals 22 and23 denote a sewn-up portion and a seam respectively. Herein, margins 24are left in the end portions so as to make it easy to sew up the endportions. Then the margins 24 are removed and the bag-shaped object isreversed. In other words, the bag-shaped object is turned inside out andoutside in. Thereby the sewn-up portion 22 is hidden inside. Next, thedummy cylindrical mold 15, which is substantially equal in diameter tothe porous cylindrical oil retaining member with which the reversedbag-shaped object is covered, is inserted through the bag-shaped object.Thereby, a fibrous layer 11 a is formed along the outer periphery of thedummy cylindrical mold 15. Herein, hot pressing can be performed so asto eliminate a bulge in the sewn-up portion 22 (FIG. 3(B)). Thereafter,the porous film 3 is bonded to the surface of the fibrous layer 11 a,and the tubular double-layer structure composed of the fibrous layer 11a and the porous film 3 is removed from the dummy cylindrical mold 15 soas to obtain the member for the oil application device of the presentinvention. This is the same procedure as that of the first method ofmanufacturing the member for the oil application device.

[0033] Next, a method of manufacturing the oil application device of thepresent invention will be described with reference to FIGS. 4 to 6.FIGS. 4(B) and 5 omit illustration of the porous film 3 constituting theoutermost layer. Before a porous cylindrical oil retaining member 2 iscovered with the member 20 for the oil application device, the innerdiameter of the member 20 for the oil application device is slightlysmaller than the outer diameter of the porous cylindrical oil retainingmember 2. Accordingly, in order to fit the porous cylindrical oilretaining member 2 with the member 20 for the oil application devicesuch that the peripheral face of the former is covered with the latter,one end portion of the porous cylindrical oil retaining member 2 isinserted into an inner hole 201 of the member 20 for the oil applicationdevice and is pressed further inwards (FIG. 4(A)). Thereby, the fibrouslayer 11 can be fixed, because of its elasticity, to the porouscylindrical oil retaining member 2 while being in close contacttherewith (FIG. 4(B)).

[0034] Further, when the porous cylindrical oil retaining member 2 iscovered with the member 20 for the oil application device, it is alsoappropriate that a felt formed into a ribbon-like shape be spirallywound around the porous cylindrical oil retaining member 2 and fixedthereto in advance and that the felt be covered with the member 20 forthe oil application device. The felt formed into the ribbon-like shapecan be of the same type as the felt formed into the cylindrical shape. Athick, high-density felt with a weight of 500 to 800 g/m², a thicknessof 2 to 3 mm, and a width of 20 to 30 mm is preferable because of itsenhanced ability to retain oil. The ribbon-like felt is fixed to theporous cylindrical oil retaining member 2 by applying an adhesive suchas silicon rubber or the like to edges of the ribbon-like felt andspirally winding the ribbon-like felt around the porous cylindrical oilretaining member 2 while fitting the adjacent edges to each other.Thereafter, the ribbon-like felt is covered with the member 20 for theoil application device. Such a structure has the thick felt layer formedas the inner layer and thus offers stable application performance.Further, this structure is preferable in that the confronting portionsof the felt that has been spirally wound exert little influence onapplication of oil.

[0035] The porous cylindrical oil retaining member 2 is not specificallylimited as long as it can retain silicon for application. For example,the porous cylindrical oil retaining member 2 is designed to retain alarge amount of silicon oil for application in a group of high-volumepores with a pore diameter of 50 to 2000 μm and a porosity of 60 to 80%,and is further fitted with a shaft 10. Such an oil retaining member 2 isdesigned such that releasing oil is retained in the large pores and thatinter-fiber gaps serve to transfer releasing oil by means ofcapillarity, thus making it possible to achieve great ability to retainoil and aging-free oil application performance. The porous cylindricaloil retaining member 2 is preferably made from a porous ceramic compactbut is not limited to the aforementioned structure. That is, it is alsopossible to use a variety of other porous materials including asponge-like material and a material having a group of pores each havinga diameter smaller than 50 μm.

[0036] The porous cylindrical oil retaining member can be manufacturedas follows. That is, one or more ceramic fibers selected from silicafiber, silica alumina fiber, alumina fiber and glass fiber, one or morekinds of ceramic particles that are selected from silica particles,silica alumina particles, alumina particles and glass particles and thatare blended with one another if need be, one or more inorganic bindersselected from silica sol, alumina sol and glass frit, organic resinparticles such as polypropylene and so on, an organic binder, and waterare used as raw materials. These raw materials are kneaded and formedinto a compact of a predetermined shape by extrusion or the like.Furthermore, the compact is dried and calcined, so that the porouscylindrical oil retaining member is obtained. The ceramic fibers to beselected have a fiber diameter of 2 to 30 μm and a fiber length of 100to 5000 μm. The ceramic particles to be selected have a particlediameter of 10 to 50 μm. The organic resin particles to be used have aparticle diameter of 200 to 2000 μm.

[0037] The above porous ceramic material is provided with a porousstructure through gasification of the organic binder, water and organicresin particles at the time of calcination. More specifically,inter-fiber gaps with a main pore diameter of 10 to 100 μm are formedthrough gasification of the organic binder and water, and large poreswith a diameter of 200 to 2000 μm are obtained through gasificationof-organic resin particles. In this porous ceramic material, the largepores serve to store up silicon oil and the inter-fiber gaps serve totransfer silicon oil by means of capillarity.

[0038] After the porous cylindrical oil retaining member 2 has beencovered with the member 20 for the oil application device, folding edges12 are formed on opposed sides of the porous cylindrical oil retainingmember 2 (FIG. 4(B)). The porous cylindrical oil retaining member 2 isimpregnated with releasing oil (application oil) while this state ismaintained. The silicon oil for application to be used herein usuallydemonstrates a low viscosity, that is, 10×10⁻⁶ to 500×10⁻⁶ m²/seconds(10 to 500 cSt) at a temperature of 25° C.

[0039] Next, the folding edges 12 protruding at opposed end portions ofthe porous cylindrical oil retaining member 2 are folded inwards so asto cover lateral faces of the porous cylindrical oil retaining member 2.In this case, the porous film 3, which is not shown in the drawings, isalso folded in the same manner. Folded portions 121 are then pressed andfixed by a fixture member. A washer 13 that has a hole for passage of ashaft formed at a central portion thereof and that has a fitting claw131 around the hole can be used as the fixture member. That is, thewasher 13 is fitted onto the shaft 10 from an end portion thereof,pressed further inwards against an elastic force of the fitting claw131, and fixed in such a manner as to press the folded portions 121 fromoutside.

[0040] Thus, the oil application device 1 is completed. FIG. 7 is a sideview showing a state where the oil application device of the presentinvention is employed in a fixing device. In FIG. 7, the oil applicationdevice, which is denoted by the reference numeral 1, is built into afixing device 4. The fixing device 4 allows a recording paper 7 to passthrough a space between a thermal fixing roll 5 and a press roll 6 so asto fix toner 8 that has been transferred to a surface 7 a of therecording paper 7. In order to prevent the toner 8 on the surface 7 a ofthe recording paper 7 from adhering to the thermal fixing roll 5, theoil application device 1 is opposed to and in contact with the thermalfixing roll 5 so as to apply silicon oil, that is, releasing oil forapplication to the thermal fixing roll 5. Thus, the oil applicationdevice is employed in a fixing device of an electronic copying machineor an electronic printing machine.

Industrial Applicability

[0041] The present invention is designed such that the porouscylindrical oil retaining member can be covered with the member for theoil application device easily, thus making it possible to fabricate theoil application device easily and enhance the overall productivity.Further, in the case where the porous cylindrical oil retaining memberis recycled, the member for the oil application device can be easilyremoved from the porous cylindrical oil retaining member, and can befixed thereto without using an adhesive during assembly. Hence, theporous cylindrical oil retaining member is prevented from being soiledwith an adhesive. Thus, the recycling cost can be reduced.

[0042] Further, the present invention is designed such that the fiberfelt can sufficiently perform the function of an oil transfer layer andthat the PTFE film can sufficiently perform the function of an oilapplication amount control layer, thus making it possible to guarantee afixing roll of uniform application of a predetermined amount of oil.

[0043] Further, the present invention is designed such that the adhesivecomponents in their solidified state are dispersed into silicon oil andexist partially inside the open pores, thus making it possible toenhance strength and durability of the porous film. On the other hand,the mixture of an adhesive and silicon oil is microscopically in a statewhere the adhesive is dispersed into silicon oil. Thus, the silicon oilarea serves as a passage for releasing oil inside the open pores.Accordingly, the open pores in the porous film are filled with themixture, whereby releasing oil is guaranteed of a passage despiteclosure of the open pores. Consequently, it becomes possible to apply asuitable amount of releasing oil and control the amount of applicationof releasing oil.

[0044] Further, the present invention makes it possible to reliablyfabricate the member for the oil application device by a simple method.Further, the sheet-like fibrous layer is formed into a cylindricalshape, whereby the number of seams can be reduced. Thus, it becomespossible to apply oil uniformly without causing irregularities.

[0045] Further, the present invention makes it possible to easilyfabricate the cylindrical member for the oil application device. Also,the invention makes it possible to suppress the influence of the sewn-upportion and to apply oil uniformly without causing irregularitiesdespite the simplicity of processes of fabrication.

[0046] Further, the present invention provides a simple structure inwhich the porous cylindrical oil retaining member is covered with thetubular member for the oil application device which has been formedseparately, thus making it possible to reduce the number of failures andachieve stable application of oil. Further, in the case where the porouscylindrical oil retaining member is recycled, the tubular member for theoil application device can be easily removed from the porous cylindricaloil retaining member. This makes it possible to enhance the workabilityduring recycling.

[0047] Further, the present invention makes it possible to fix thetubular member for the oil application device to the porous cylindricaloil retaining member without using an adhesive.

1. A tubular member for an oil application device which has been formedseparately so as to cover a peripheral face of a porous cylindrical oilretaining member, wherein: the tubular member for the oil applicationdevice has a multi-layer structure including an inner layer and anoutermost layer; the inner layer is a fibrous layer; and the outermostlayer is a porous film.
 2. The member for the oil application deviceaccording to claim 1, wherein: the fibrous layer is a fiber felt; andthe porous film is a PTFE film.
 3. The member for the oil applicationdevice according to claim 1, wherein: the fibrous layer is a fiber felthaving a three-dimensional flexible network structure with a weight of200 to 800 g/m², a thickness of 1 to 5 mm, and a density of 170 to 260kg/m³.
 4. The member for the oil application device according to claim1, wherein: the porous film is a PTFE film with a surface roughness Raof 0.7 to 0.8 μm, a thickness of 20 to 100 μm, a gas permeability of 5to 100 seconds/100 cc, an open pore diameter of 0.05 to 2.0 μm, and anopen porosity of 70 to 90%.
 5. The member for the oil application deviceaccording to claim 1, wherein: the fibrous layer and the porous film arebonded together by the mixture of an adhesive and silicon oil.
 6. Amethod of manufacturing a member for an oil application device,comprising the steps of: winding a sheet-like fibrous material, which islonger than a circumferential length of a dummy cylindrical mold that issubstantially equal in diameter to a porous cylindrical oil retainingmember to be covered, around the dummy cylindrical mold by one turn soas to form a fibrous layer; sewing up bonded portions; pressing at leastthe bonded portions so as to form a peripheral face; and winding asheet-like porous film around the peripheral face of the fibrous layerby one turn so as to bond the sheet-like porous film to the fibrouslayer.
 7. A method of manufacturing a member for an oil applicationdevice, comprising the steps of: folding a sheet-like fibrous materialin two and sewing up end portions thereof; reversing the sheet-likefibrous material that has been sewn up and covering a dummy cylindricalmold, which is substantially equal in diameter to a porous cylindricaloil retaining member to be covered, with the sheet-like fibrousmaterial; and winding a sheet-like porous film around a surface of thesheet-like fibrous material covering the dummy cylindrical mold by oneturn so as to bond the sheet-like porous film to the sheet-like fibrousmaterial.
 8. An oil application device having a porous cylindrical oilretaining member that is covered on a peripheral face thereof with atubular member for the oil application device which has been formedseparately, wherein: the tubular member for the oil application devicehas a multi-layer structure including an inner layer and an outermostlayer; the inner layer is a fibrous layer; and the outermost layer is aporous film.
 9. The oil application device according to claim 8,wherein: the tubular member for the oil application device is folded atopposed end portions thereof onto lateral faces of the porouscylindrical oil retaining member; and folded portions of the tubularmember for the oil application device are pressed and fixed by a fixturemember.
 10. The oil application device according to claim 8, wherein:the oil application device is employed in a fixing device of anelectronic copying machine or an electronic printing machine.